1. Field of the Invention
The present invention relates to car air conditioning equipment.
2. Description of Prior Art
Conventional car air conditioning equipment is provided with an air feeding device for feeding air, a temperature adjusting device for adjusting the temperature of the air fed from the air feeding device by heating/cooling and mixing the air, air-blow outlets for blowing the air with its temperature adjusted by the temperature adjusting device into a car interior, an interior temperature detector for detecting the temperature in the car interior, and a temperature control device for controlling the air feeding device and the temperature adjusting device so that the interior-temperature detected by the interior-temperature detector is made to be a previously set interior-temperature.
In such car air conditioning equipment, the temperature of air blown into the car room varies monotonically toward a previously set interior-temperature, and if the blown-air temperature becomes the set interior-temperature, the blown-air temperature becomes fixed and does not vary.
However, if the interior-temperature is maintained at a previously set comfortable value for a long time after it has reached the comfortable value, an occupant of the car becomes acclimatized to the comfortable temperature to thereby lose a comfortable feeling and comes to have a stagnant feeling and thereby an uncomfortable feeling.
There has been proposed car air conditioning equipment in which the flow and direction of blown-air are changed temporally in order to prevent the occupant in the car from having such a stagnant feeling and thereby an uncomfortable feeling (U.S. Pat. No. 4,495,560).
In this method of changing the flow of blown-air, however, a change in sound level is caused as the flow of blown-air varies. If the sound level varies, the human hearing sense is strongly aware of the sound as a noise even when the sound level is low. Thus, in this method, an uncomfortable feeling for the sound may be caused invariably even if the occupant becomes thermally comfortable. Accordingly, this method is unsuitable as an air conditioning method to obtain a comfortable feeling. Further, in this method, the flow of air is changed in view of the entire interior, so that a delay occurs in realizing a comfortable feeling.
In the method of changing the direction of air, on the other hand, the occupant loses an a feeling of the existence of air conditioning feeling and hence has an uncomfortable feeling when the direction of the blown air is changed so that the blown-air does not to blow on the occupant. Accordingly, this method is unsuitable as an air conditioning method to obtain a comfortable feeling.
In some ordinary air conditioning equipment which is not car air conditioning equipment, on the other hand, the blown-air temperature is changed as time passes so as to prevent a person from being acclimatized to a comfortable temperature to thereby lose a comfortable feeling.
In ordinary air conditioning equipment, however, if there occurs an external disturbance due to a change in output of a temperature adjusting device or a change in the open air temperature, a change in intensity of sunshine, etc., the blown-air temperature does not vary as desired, so that a comfortable feeling cannot be obtained.
Accordingly, this method is unsuitable as car air conditioning equipment in which an external disturbance as described above is caused frequently.